US 11,907,123 B2Granted

Flash memory garbage collection

AssigneeInternational Business Machines Corporation

InventorsRobert Edward Galbraith, Daniel Frank Moertl, Rick A. Weckwerth, Matthew Szekely

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Abstract

Embodiments include methods, systems and computer program products for managing a flash memory device. Aspects include monitoring a percentage of memory of the flash memory device that is in a ready to use state. Aspects also include operating the flash memory device in a first operating mode based on a determination that the percentage is greater than a first threshold value. Aspects further include operating the flash memory device in a second operating mode based on a determination that the percentage has fallen below the first threshold value. Aspects include operating the flash memory device in a third operating mode until the percentage exceeds the first threshold value based on a determination that the percentage has fallen below a second threshold value, which is lower than the first threshold value. The erasing of ready to erase memory block stripes is only performed during the third operating mode.

Claims15

Dependent claims

A method for managing a flash memory device, the method comprising:

monitoring a percentage of memory of the flash memory device that is in a ready to use state, wherein the flash memory device includes a plurality of dies each comprising a plurality of memory block stripes;
based on a determination that the percentage is greater than a first threshold value, operating the flash memory device in a first operating mode;
based on a determination that the percentage has fallen below the first threshold value;
operating the flash memory device in a second operating mode;
and
based on a determination that the percentage has fallen below a second threshold value, which is lower than the first threshold value, operating the flash memory device in a third operating mode until the percentage exceeds the first threshold value,
maintaining a heat level for each of the plurality of memory block stripes on each of the plurality of dies;
maintaining an operational state of each of the plurality of dies,
identifying one of the plurality of memory block stripes for filling with an data set based on a heat level of the data set, the operational state of plurality of dies and the heat level for each of the plurality of memory block stripes, wherein the one of the plurality of memory block stripes for filling is selected to have a heat level that is equal to the heat level of the data set,
wherein erasing of ready to erase memory block stripes is only performed during the third operating mode, and
wherein the third operating mode includes:
selecting a ready to erase memory block for erasure, wherein the selecting of the ready to erase memory block for erasure includes prioritizing erasure of block stripes located on dies that are not currently being used for a fill operation and selecting a block stripe in a round-robin fashion based on a determination that all dies are currently being used for fill operation;
erasing the selected ready to erase memory block;
and
marking the erased memory block as ready to use.

12 more elements

A computer program product, comprising:

a storage device;
and
program code stored in the storage device, wherein the program code, when executed by a controller that controls a non-volatile memory array of a data storage system, causes the controller to:
monitor a percentage of memory of the flash memory device that is in a ready to use state, wherein the flash memory device includes a plurality of dies each comprising a plurality of memory block stripes;
based on a determination that the percentage is greater than a first threshold value, operate the flash memory device in a first operating mode;
based on a determination that the percentage has fallen below the first threshold value;
operate the flash memory device in a second operating mode;
based on a determination that the percentage has fallen below a second threshold value, which is lower than the first threshold value, operate the flash memory device in a third operating mode until the percentage exceeds the first threshold value,
maintain a heat level for each of the plurality of memory block stripes on each of the plurality of dies;
maintain an operational state of each of the plurality of dies, and
identify one of the plurality of memory block stripes for filling with an data set based on a heat level of the data set, the operational state of plurality of dies and the heat level for each of the plurality of memory block stripes, wherein the one of the plurality of memory block stripes for filling is selected to have a heat level that is equal to the heat level of the data set,
wherein erasing of ready to erase memory block stripes is only performed during the third operating mode, and
wherein the third operating mode includes:
selecting a ready to erase memory block for erasure, wherein the selecting of the ready to erase memory block for erasure includes prioritizing erasure of block stripes located on dies that are not currently being used for a fill operation and selecting a block stripe in a round-robin fashion based on a determination that all dies are currently being used for fill operation;
erasing the selected ready to erase memory block;
and
marking the erased memory block as ready to use.

14 more elements

A data storage system, comprising:

a controller configured to be coupled to a non-volatile memory array, wherein the controller is configured to:
monitor a percentage of memory of the flash memory device that is in a ready to use state, wherein the flash memory device includes a plurality of dies each comprising a plurality of memory block stripes;
based on a determination that the percentage is greater than a first threshold value, operate the flash memory device in a first operating mode;
based on a determination that the percentage has fallen below the first threshold value;
operate the flash memory device in a second operating mode;
and
based on a determination that the percentage has fallen below a second threshold value, which is lower than the first threshold value, operate the flash memory device in a third operating mode until the percentage exceeds the first threshold value,
maintain a heat level for each of the plurality of memory block stripes on each of the plurality of dies;
maintain an operational state of each of the plurality of dies, and
identify one of the plurality of memory block stripes for filling with an data set based on a heat level of the data set, the operational state of plurality of dies and the heat level for each of the plurality of memory block stripes, wherein the one of the plurality of memory block stripes for filling is selected to have a heat level that is equal to the heat level of the data set,
wherein erasing of ready to erase memory block stripes is only performed during the third operating mode, and
wherein the third operating mode includes:
selecting a ready to erase memory block for erasure, wherein the selecting of the ready to erase memory block for erasure includes prioritizing erasure of block stripes located on dies that are not currently being used for a fill operation and selecting a block stripe in a round-robin fashion based on a determination that all dies are currently being used for fill operation;
erasing the selected ready to erase memory block;
and
marking the erased memory block as ready to use.

13 more elements

Dependencies are inferred from the claim text.

Facts

Application: 17/234,897Filed 20 Apr 2021
Published: US 2022/0334967 A120 Oct 2022
Granted: 20 Feb 2024
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

G06F 12/0804
Addressing of a memory level in which the access to the desired data or data block requires associative addressing means, e.g. caches: with main…
G06F 12/0246
Memory management in non-volatile memory, e.g. resistive RAM or ferroelectric memory: in block erasable memory, e.g. flash memory
G06F 12/0253
Free address space management: garbage collection, i.e. reclamation of unreferenced memory
G06F 2212/1016
Providing a specific technical effect: performance improvement

Family

US 2022/0334967 A1Pre-grant publication · published 20 Oct 2022
US 11,907,123 B2This patent

From the US filing history. Foreign family members aren’t listed.

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